I. Field of the Invention
This invention relates to wiper systems and, more particularly, to a drill pipe wiper system for removing materials from an outer surface of an existing drill pipe while the existing drill pipe is being removed from a ground surface.
Well drilling units are employed in prospecting for gaseous and liquid minerals and for bringing them to the surface. Because of the need for drilling to greater depths, as well as improving the speed of the drilling operation, traditional precision drilling techniques have been superseded by continuous rotary drilling. Rotary drilling utilizes rotational motion of a bit to drill the well bore. The bit is attached to a drill string which is comprised of drill collars, a drill pipe and a kelly joint. At the surface, rotational motion is imparted on the drill string by a rotary table to which the kelly joint is attached.
The drill cuttings produced by the bit that operates at the bottom of the well bore are carried to the earth's surface by circulating drilling fluids, i.e. drilling mud. The drilling fluids are continuously pumped down the well bore. The drill string must be removed periodically to replace worn bits and damaged drill pipe, also known as “tripping out.” During tripping out, drilling fluids spill from the drill pipe. Such spillage wastes the drilling fluids and exposes rig workers to unsafe working conditions. To prevent fluid drainage from the drill pipe during tripping out, workers use pipe wipers to wipe the drill pipe as the pipe is removed.
II. Description of the Known Art
Patents and patent applications disclosing relevant information are disclosed below. These patents and patent applications are hereby expressly incorporated by reference in their entirety.
U.S. Pat. No. 5,101,896 issued to Thompson et al. on Apr. 7, 1992 (“the '896 patent”) teaches a system for washing and cleaning sections of drill pipe being tripped out of the hole, and the system including a cylindrical housing having a central opening therethrough, the cover sections movable between open and closed positions by hinged joint along one edge, utilizing a system of hydraulic system cylinders, and in the closed position, maintain closed for defining a chamber therewithin. Within the housing chamber, the '896 patent teaches that there is further included a wiper member, which comprises a circular member of rubberized material having a bore through its central axis through which sections of pipe travel during the cleaning process, the bore being a width so as to frictionally engage and wipe the wall of a section of drill pipe. The wiper taught by the '896 patent would be spaced apart from the housing and housed within an annular channel along the inner surface of the housing so that the wiper would be stationary within the housing as the housing is placed in the closed position.
U.S. Pat. No. 4,690,213 issued to Stannard et al. on Feb. 3, 1986 (“the '213 patent”) teaches a pipe wiper device and system for stripping fluid from the external surface of tubular articles being pulled from the wellhead of a well. The wiper device taught by the '213 patent includes a container having a carriage movably mounted therein. A pair of wiper pad assemblies taught by the '213 patent are carried by the carriage and movable inwardly and outwardly with respect to each other. A pair of opposed actuators taught by the '213 patent are provided for moving the wiper pad assemblies inward and outward with respect to each other and the connection between the wiper pad assemblies and actuators is such that the wiper pad assemblies and carriage are movable perpendicular to the direction of actuation of the actuators thereby to accommodate sideways movement of the carriage. The actuators taught by the '213 patent are operated by a system that automatically retracts the wiper pad assemblies responsive to rig standpipe pressure so that the wiper pad assemblies retract automatically during drilling.
U.S. Pat. No. 7,621,344 issued to Frey on Nov. 24, 2009 (“the '344 patent”) teaches a drill pipe wiper system that includes a plurality of coextensively shaped rectilinear support rails with axially opposed ends with a plurality of openings formed in the opposed ends of the support rails, a plurality of ports penetrating an outer surface of the support rails, and a plurality of spring-loaded latch pins. The system taught by the '344 patent further includes a plurality of coextensively shaped rectilinear end rails and a mechanism for attaching the support rails to a support surface.
U.S. Pat. No. 6,155,388 issued to Brown on Dec. 5, 2000 (“the '388 patent”) teaches a wiper device that comprises an elongated conveyor arm which can pivot in a horizontal plane and freely move forward and backward through a limited travel (which movement capabilities are collectively termed “floating” capability). The arm taught by the '388 patent carries a wiper pad assembly on its outer end. The wiper pad assembly taught by the '388 patent can therefore float with the arm to accommodate lateral and to and fro sway of the drill string within the confines of the rig rotary table bushing, when the wiper pads are engaged with the drill string. The arm taught by the '388 patent can be advanced and withdrawn to convey the wiper pad assembly between the operative stripping position over the bushing and a retracted position off to one side of the bushing.
U.S. Pat. No. 5,842,252 issued to Cameron on Dec. 1, 2008 (“the '252 patent”) teaches a pipe wiper assembly for stripping fluid from oil and gas well strings which has a pair of rams which can move from a first remote position relative to the pipe forward to a second position contacting and wiping the pipe and forward to a third position when the pipe is not in the oil or gas well to protectively cover the well, the rams being mounted in a carrier which has freedom of movement in any radial direction to allow the rams to be centralized around the oil or gas well string. The unit taught by the '252 patent having alignment guides such that when the rams are returned to the first position the rams and carrier will be centralized over the well bore and the freedom of radial movement is eliminated.
U.S. Pat. No. 5,170,853 issued to Mason et al. on Dec. 15, 1992 (“the '853 patent”) teaches a pipe wiper assembly which comprises a first housing for supportingly receiving at least one resilient wiper member, and a second housing supported above the well bore for connecting the first housing to the stack assembly of the drilling unit. The first and second housings taught by the '853 patent are interconnected such that the first housing is selectively movable in response to vertical deviations of the drill pipe as the drill pipe is withdrawn from the vertically extending well bore.